In the poor Varta's defence, I have never seen one fail or leak... It's quite amazing that those things can still hold a charge after all these years...
My 2x800k SE has one and it's the only one I didn't remove. And let me tell you I'm not the kind of guy who trusts any kind of battery (Nearly all remotes and appliances around the house are battery-less for a reason.)
Edit: BTW, what kind of daughter board is that? Is that an accelerator?